using System.Web;
using System.Web.UI;
using System.IO;
/// <summary>
/// This is to cope with postbacks and the URL rewriter - without it the urls revert to 
/// their original form on postback and this can cause viewstate errors
/// </summary>

public class FormRewriterControlAdapter : System.Web.UI.Adapters.ControlAdapter
{

    protected override void Render(System.Web.UI.HtmlTextWriter writer)
    {
        base.Render(new RewriteFormHtmlTextWriter(writer));
    }

}

public class RewriteFormHtmlTextWriter : HtmlTextWriter
{
    public RewriteFormHtmlTextWriter(HtmlTextWriter writer):base(writer)
    {
        InnerWriter = writer.InnerWriter;
    }
    public RewriteFormHtmlTextWriter(TextWriter writer):base(writer)
    {
        InnerWriter = writer;
    }

    public override void WriteAttribute(string name, string value, bool fEncode)
    {
        // if the attribute we are writing is the "action" attribute, and we are not on a sub-control, 
        // then replace the value to write with the raw URL of the request - which ensures that we//ll
        // preserve the PathInfo value on postback scenarios

        if (name == "action")
        {
            HttpContext Context = HttpContext.Current;

            if (Context.Items["ActionAlreadyWritten"] == null)
            {
                // Because we are using the UrlRewriting.net HttpModule, we will use the 
                // Request.RawUrl property within ASP.NET to retrieve the origional URL
                // before it was re-written.  You//ll want to change the line of code below
                // if you use a different URL rewriting implementation.

                value = Context.Request.RawUrl;

                // Indicate that we//ve already rewritten the <form>//s action attribute to prevent
                // us from rewriting a sub-control under the <form> control

                Context.Items["ActionAlreadyWritten"] = true;
            }
        }

        base.WriteAttribute(name, value, fEncode);
    }
}